Lazard Insights The Art and Science of Volatility Prediction Stephen Marra, CFA, Director, Portfolio Manager/Analyst Summary Statistical properties of volatility make this variable forecastable to some degree. This is one of the most profound findings in financial economics with far-reaching implications for asset allocation. The relationship between risk (volatility) and returns is not constant. If one assumes this relationship holds through all environments, this implies that only a static asset allocation is sufficient. However, risk-return patterns can fluctuate dramatically, as such: volatility forecasting models are often used to improve upon static allocations through volatility targeting. There are almost infinite possibilities in terms of designing a volatility forecasting model. In our view, simpler, broader models are preferable over more complex ones which can lead to overconfident predictions. Return streams across asset classes differ, so the statistical properties of volatility differ as well. This means that certain asset classes are better suited than others for a volatility targeting approach. Introduction Uncertainty is inherent in every financial model. While there are many ways to quantify this uncertainty, volatility is the most widely accepted barometer for this measure. The most practical and straightforward way to measure volatility is as a statistical measure of the dispersion of market returns over a particular period. As a result, volatility has effectively become the expected price of uncertainty in markets. One of the most profound findings in financial economics is that volatility can to a large extent be forecasted. Predictability follows from some of the statistical properties of volatility. The implications of volatility forecasts are evident in several ways. Volatility reaches all corners of the economy. Inaccurate volatility estimates can leave financial institutions without enough capital for operations and investment. Market volatility and its impact on public confidence can have a significant effect on the broader global economy. So, the trade-off between risk (volatility) and return is critical for all investment decisions. In addition, we believe there are relationships between volatility and asset returns that make it possible to systematically increase the risk-adjusted returns on investments (to varying degrees) by applying volatility forecasts to asset allocation decisions. Lazard Insights is an ongoing series designed to share valueadded insights from Lazard s thought leaders around the world and is not specific to any Lazard product or service. This paper is published in conjunction with a presentation featuring the author. The original recording can be accessed via www.lazardnet.com/insights.
2 Volatility Is Not Constant It would not make much sense to produce forecasts for a variable that does not change much weather forecasters would not be needed if it was 8 degrees and sunny 365 days a year. In financial markets, volatility is not constant. Any strategic or tactical asset allocation decision is ultimately governed by the trade-off between risk and reward. Conventional wisdom says that greater return is compensation for greater risk. Assuming a constant relationship between risk and reward leaves only the investor s risk tolerance as the determining factor for a fixed asset allocation: maximize return at a particular level of risk; or minimize risk at a particular level of target return. Managing portfolios in this way assumes that a static relationship between risk and return exists in all environments and implies a fixed asset allocation. While the relationship between risk and return appears constant over long periods, the relationship fluctuates dramatically when analyzing it over shorter time frames. For example, over a 35+ year span and using US equities and bonds data, one can see that the risk-reward profile of equities and fixed income has been quite different through the decades (Exhibit 1). During the 199s for example, equities added almost 1% annualized return for a roughly 1% increase in volatility. Whereas, in the first decade of the 2s, equities actually detracted almost 8% annualized for the 13% they added in volatility. The lack of uniformity of this risk-return profile indicates to us that opportunities existed during the period studied to add considerable value both from return enhancement as well as risk reduction from an asset allocation process that was more active. In our view, this argues against having a fixed asset allocation and moving towards a more active asset allocation approach. In addition, the inclusion of asset classes beyond global equities and bonds specific factor exposures for example would make the relationship between risk and return even more unstable and less consistent. Forecasting Volatility Is Possible because of Key Statistical Features Latency (or volatility clustering) is the characteristic denoting that periods of both high and low volatility tend to persist. This follows from the observation that large changes in asset returns tend to be immediately followed by large changes; the same is true for small changes. To illustrate this, we calculated the autocorrelation (i.e., the correlation of one asset s return to itself) of the absolute value of returns for three equity indices at different time lags (Exhibit 2). Using the absolute value of the returns enabled us to focus on the change in magnitude of the return rather than the direction of the return. The magnitude of future returns is dependent on the magnitude of past returns, with this dependence becoming weaker over time. As a result of this relationship, past volatility actually has a reasonable amount of explanatory or predictive power over future volatility. The latency of volatility makes it significantly more forecastable than asset returns. Exhibit 1 Risk-Reward Is Not Static Efficient Frontiers for Sub-Periods Return (%) 2 15 1 5 1% Bonds 1% -5 3 6 9 12 15 18 Volatility (%) 198s 199s 2s 21 216 198 216 For the period January 198 to May 216 = S&P 5 Index; Bonds = Barclays Capital US Aggregate Bond Index. The performance quoted represents past performance. Past performance does not guarantee future results. The indices listed above are unmanaged and have no fees. It is not possible to invest in an index. Index performance does not represent the performance of any product managed by Lazard. Exhibit 2 Autocorrelation of Global Equity Returns: The Magnitude of Returns Shows Some Dependence Autocorrelation of Absolute Value of Returns.4.3.2.1. -.1 5 1 15 S&P 5 Index MSCI EM MSCI ACWI Another notable characteristic of volatility is the negative and asymmetric relationship between returns and volatility. The calculation of volatility is indifferent to the direction of the market. However, volatility generally rises when the market falls and volatility tends to fall when the market rises (Exhibit 3, page 3). It has been theorized that this relationship is fundamental in nature and is due to what is called the leverage effect. The leverage effect posits that as stock prices fall, companies become more leveraged as the value of their debt rises relative to the value of their equity. As a result, the stock price becomes more volatile. 2 25 3 35 Lag (weeks) For the period January 1999 to October 215, weekly returns The performance quoted represents past performance. Past performance is not a guarantee of future results. This is not intended to represent any product or strategy managed by Lazard. It is not possible to invest directly in an index.
3 Exhibit 3 There Is a Negative Relationship between Returns and Volatility Change in VIX on Negative S&P 5 Index Days Change in VIX (%) 6 4 2-2 Beta: -3.9 R-squared:.36-4 -12-1 -8-6 -4-2 Change in S&P 5 Index (%) Change in VIX on Positive S&P 5 Index Days Change in VIX (%) 6 4 2-2 -4 Beta: -2.8 R-squared:.23 2 4 6 8 1 12 Change in S&P 5 Index (%) For the period January 199 to October 215, daily returns The performance quoted represents past performance. Past performance is not a guarantee of future results. This is not intended to represent any product or strategy managed by Lazard. It is not possible to invest directly in an index. In addition to this negative correlation, the magnitude of the impact on volatility is significantly larger for downward market moves than it is when the market moves higher. Based on Exhibit 3, the beta of the VIX Index to the S&P 5 Index on negative return days was -3.9 with an r-squared of.36 whereas on positive return days the beta was -2.8 with an r-squared of.23. The volatility feedback effect suggests that as volatility rises and is priced into the market, there is a commensurate rise in the required return on equity as investors place a higher hurdle rate on returns to achieve their desired risk-adjusted upsides. This leads to an instant decline in stock prices as the volatility immediately reduces the risk-adjusted attractiveness of equities. The last property we will discuss is mean reversion volatility tends to revert to a long-term mean. Exhibit 4 shows the behavior of the VIX Index when it is in the top and bottom decile of its historical distribution as it moves back to a long-term average. One can also see that the degree and speed of mean reversion is more pronounced when the level of volatility is high compared to when it is low. The prevailing thesis behind the mean reverting nature of volatility is related to investor psychology. In periods of low volatility, investors reduce their expectations and thresholds for volatility and as a result, become more sensitive to near-term news flow. This leads to a larger reaction function to new information and higher volatility as a result. Conversely, during periods of elevated volatility investors will increase their expectations and thresholds for volatility and become less sensitive to new information. This should result in lower levels of volatility in subsequent periods. Models for Volatility Forecasting The statistical properties of volatility discussed in the preceding section make volatility inherently predictable to a sufficient degree to be useful to practitioners. There are a number of different models that can be used to forecast volatility, which incorporate different degrees of these characteristics. Moreover, models have varying degrees of Exhibit 4 Reversion to the Mean Top/Bottom VIX Observations Converge to the Long-Term Average VIX 4 3 2 1 4 From High Long-Term Average From Low 8 12 16 2 24 Weeks after observation in top/bottom 1% For the period 5 January 199 to 22 April 216 Based on the top/bottom 1% of weekly observations, we tracked the pattern for 24 weeks and aggregated the top/bottom deciles by average. Source: CBOE, Haver Analytics success when dealing with different asset classes. In brief, some of the most well-known models are: HIS: Historical models are the most straightforward, using calculations ranging from as simple as a historical mean to moving averages with different weighting schemes (to balance short- and long-term fluctuations). Autoregressive Models: This includes a whole library of methods involving the statistical technique of regressions with a lag of the original data series as predictors. Implied Standard Deviation: These models take information from option markets to calculate the implied volatility. We discuss these methodologies in greater detail in our paper Predicting Volatility. 1 The takeaway here would be that there are end-
4 less possibilities to design a forecasting model with inherent trade-offs as it relates to the volatility properties one wishes to capture. In our view, a good forecasting model captures all of the key characteristics of volatility with a healthy dose of humility. After all, financial markets are not akin to physical sciences which behave according to some prescribed laws of nature. The standard statistical view assumes that there is some constant and unknown underlying structure to markets. This has led statisticians to build models that are extremely specific and complex. These excessive levels of complexity and precision belie the random nature of future asset prices and engender dangerous levels of overconfidence that these models can predict future events with a high degree of certainty. Consequently, simpler, broader models which are able to capture the more general features of volatility and financial returns will likely provide more robust and transparent predictive abilities over longer, out-of-sample time horizons. Applications of Volatility Forecasting: Volatility Targeting We have shown that the risk reward trade-off is not constant particularly over shorter time frames. This means that a static asset allocation can be ineffective. With this in mind, volatility forecasting models are often used to improve upon a fixed asset allocation framework by allocating to a fixed level of volatility instead. This is known as volatility targeting and enables a portfolio to potentially take advantage of volatility forecasts and make allocation decisions. The return streams of different asset classes display differing degrees of these characteristics (Exhibit 5). The ones which exhibit more of the aforementioned characteristics are better candidates for volatility targeting. To illustrate the success of volatility targeting on different asset classes we examined each asset class individually and then in combination with cash picking a volatility target. The measure of success is the Sharpe ratio, a measure of risk-adjusted return. The more an asset class is favored by volatility forecasting characteristics, the more risk targeting improves the results (Exhibit 6). Since US Treasuries exhibit none of the volatility forecasting features, the impact from volatility targeting on the risk-adjusted return is minimal., on the other hand, strongly exhibit all of the characteristics. Hence, a volatility targeting approach can have a significant positive effect on the resulting Sharpe ratio. The impact on commodities and high yield fixed income is minimal; although the latter has many characteristics that would favor volatility targeting, it does not have a strong negative correlation between volatility and returns. Exhibit 5 Volatility Properties Differ by Asset Class Volatility Clustering Effect Negative Correlation between Volatility and Returns Fat Tails (Non- Normality) Leverage Effect DM US EM Commodities High Yield Fixed US Income Treasuries Strong Strong Strong Strong Strong Weak Strong Strong Strong Weak Weak Weak Strong Strong Strong Weak Strong Weak Strong Strong Strong Weak Strong Weak For the period May 22 to May 216 DM = MSCI World Index; US = S&P 5 Index; EM = MSCI Emerging Markets Index; Commodities = Bloomberg Commodity Index; High Yield Fixed Income = Barclays Global High Yield Index; US Treasuries = Barclays US Treasury Index. Exhibit 6 Results by Asset Class Risk-Adjusted Results Comparison, 22 216 Sharpe Ratio 1.6 1.2.8.4. -.4 Stand-Alone Sharpe Ratio Volatility-Targeted Sharpe Ratio Developed Markets US Emerging Markets Commodities High Yield Fixed Income US Treasuries For the period May 22 to May 216 Developed Markets = MSCI World Index, volatility target 12%; US = S&P 5 Index, volatility target 12%; Emerging Markets = MSCI Emerging Markets Index, volatility target 12%; Commodities = Bloomberg Commodity Index, volatility target 12%; High Yield Fixed Income = Barclays Global High Yield Index, volatility target 7%; US Treasuries = Barclays US Treasury Index, volatility target 4%. The performance quoted represents past performance. Past performance is not a guarantee of future results. This is not intended to represent any product or strategy managed by Lazard. It is not possible to invest directly in an index. Because a volatility targeting strategy involves being under-exposed to an asset class when its volatility is high and completely exposed when its volatility is low, a strong negative relationship between volatility and returns is a pre-requisite for volatility targeting. High yield fixed income markets have historically experienced some of their strongest returns in periods when volatility was very high in the 15% 2% range.
5 Conclusion Uncertainty is at the center of all financial models and volatility is the practical measure of that uncertainty. We should note that volatility and its relationship with returns is not constant, which makes volatility forecasting a worthwhile effort. Fortunately, several characteristics of financial return series make volatility inherently predictable. As a result, we believe forecasting volatility has important implications for all investors that are focused on risk-adjusted returns. Forecasting methodologies are quite diverse and vary in their degrees of complexity and accuracy. They incorporate varying degrees of these common characteristics of financial return series, with varying degrees of specification to a particular data sample. Volatility targeting is one method of utilizing a forecasting model to leverage the dynamic relationship between returns and risk in an asset allocation framework. Different asset classes possess differing degrees of these statistical characteristics. This is the key driver of the impact that volatility targeting can have on risk-adjusted returns. in general have the best combination of these volatility properties which leads to favorable risk-adjusted results from a volatility targeting approach.
6 This content represents the views of the author(s), and its conclusions may vary from those held elsewhere within Lazard Asset Management. Lazard is committed to giving our investment professionals the autonomy to develop their own investment views, which are informed by a robust exchange of ideas throughout the firm. Notes 1 Paper available at: http://www.lazardnet.com/docs/sp/2243/predictingvolatility_lazardresearch.pdf Important Information Published on 7 September 217. This document reflects the views of Lazard Asset Management LLC or its affiliates ( Lazard ) based upon information believed to be reliable as of 3 June 216. There is no guarantee that any forecast or opinion will be realized. This document is provided by Lazard Asset Management LLC or its affiliates ( Lazard ) for informational purposes only. Nothing herein constitutes investment advice or a recommendation relating to any security, commodity, derivative, investment management service or investment product. Investments in securities, derivatives and commodities involve risk, will fluctuate in price, and may result in losses. Certain assets held in Lazard s investment portfolios, in particular alternative investment portfolios, can involve high degrees of risk and volatility when compared to other assets. Similarly, certain assets held in Lazard s investment portfolios may trade in less liquid or efficient markets, which can affect investment performance. Past performance does not guarantee future results. The views expressed herein are subject to change, and may differ from the views of other Lazard investment professionals. This document is intended only for persons residing in jurisdictions where its distribution or availability is consistent with local laws and Lazard s local regulatory authorizations. Please visit www.lazardassetmanagement.com/globaldisclosure for the specific Lazard entities that have issued this document and the scope of their authorized activities. Equity securities will fluctuate in price; the value of your investment will thus fluctuate, and this may result in a loss. Securities in certain non-domestic countries may be less liquid, more volatile, and less subject to governmental supervision than in one s home market. The values of these securities may be affected by changes in currency rates, application of a country s specific tax laws, changes in government administration, and economic and monetary policy. Emerging markets securities carry special risks, such as less developed or less efficient trading markets, a lack of company information, and differing auditing and legal standards. The securities markets of emerging markets countries can be extremely volatile; performance can also be influenced by political, social, and economic factors affecting companies in these countries. An investment in bonds carries risk. If interest rates rise, bond prices usually decline. The longer a bond s maturity, the greater the impact a change in interest rates can have on its price. If you do not hold a bond until maturity, you may experience a gain or loss when you sell. Bonds also carry the risk of default, which is the risk that the issuer is unable to make further income and principal payments. Other risks, including inflation risk, call risk, and pre-payment risk, also apply. High yield securities (also referred to as junk bonds ) inherently have a higher degree of market risk, default risk, and credit risk. Securities in certain non-domestic countries may be less liquid, more volatile, and less subject to governmental supervision than in one s home market. The values of these securities may be affected by changes in currency rates, application of a country s specific tax laws, changes in government administration, and economic and monetary policy. Emerging markets securities carry special risks, such as less developed or less efficient trading markets, a lack of company information, and differing auditing and legal standards. The securities markets of emerging markets countries can be extremely volatile; performance can also be influenced by political, social, and economic factors affecting companies in these countries. Derivatives transactions, including those entered into for hedging purposes, may reduce returns or increase volatility, perhaps substantially. Forward currency contracts, and other derivatives investments are subject to the risk of default by the counterparty, can be illiquid and are subject to many of the risks of, and can be highly sensitive to changes in the value of, the related currency or other reference asset. As such, a small investment could have a potentially large impact on performance. Use of derivatives transactions, even if entered into for hedging purposes, may cause losses greater than if an account had not engaged in such transactions. Certain information included herein is derived by Lazard in part from an MSCI index or indices (the Index Data ). However, MSCI has not reviewed this product or report, and does not endorse or express any opinion regarding this product or report or any analysis or other information contained herein or the author or source of any such information or analysis. MSCI makes no express or implied warranties or representations and shall have no liability whatsoever with respect to any Index Data or data derived therefrom. RD199